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Finding the Fourth Proportional to 915.65, 1,372.17 and 420.84

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Solution

The fourth proportional to 915.65, 1,372.17 and 420.84 is: 630.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    915.65 : 1,372.17 = 420.84 : x
  2. Step 2: Convert to fraction form
    915.65/1,372.17 = 420.84/x
  3. Step 3: Cross multiply
    915.65x = 1,372.17 × 420.84
  4. Step 4: Simplify right side
    915.65x = 577,464.02
  5. Step 5: Solve for x
    x = 577,464.02/915.65
  6. Step 6: Final answer
    x = 630.66

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.